Since living for some time in Germany and buying bread made in real wood-fired ovens, I’ve wanted to build an outdoor oven to go with all my other outdoor kitchen stoves. My wife bought me the Uuni3 for my birthday, and the package included two bags of special food grade wood pellets. ($25 for 22 pounds!) https://uuni.net/
When the pizza stone reaches 932 F according to a dual laser thermometer, the pizza is placed in the oven and is done in 60 seconds. This is for a thin crust Neapolitan type Pizza. She also bought me the cast-iron sizzler pan for steaks and vegetables. Sometimes, after we make pizza, and there is still quite a bit of heat on the stone, I make some flat breads, with a bit of that wood fired char taste.
Getting back to Senne’s flame photo, my first thought was that he may have had a grate similar to the one in the pellet burner for the Uuni3, where a very large flame is actually desired.
There is a large Facebook group covering Uuni modifications, and another one dealing with recipes and results (Pizza). I believe this last photo of the two flares came from a posting on the FB group, and I can’t give proper credit. There is a new version called the Uuni Pro which has options for pellets, wood, charcoal, or propane as the fuel. It is more expensive.